The present invention relates to a bracket arrangement for supporting the weld area of an elongated body, such as a pole, which extends off a base, off a foundation, or even off another pole. More particularly, it relates to a bracket arrangement that also includes a vibration dampening element.
Static spikes (also referred to as static dischargers) are elongated bodies that often are installed atop buildings or tall poles in order to harmlessly dispel static electricity charges. Static spikes typically are schedule 40 metal poles, 2-inches in diameter, and between 10 feet and 25 feet long. The static spike is welded to a flange which is then bolted onto the distal end of the structure to be protected (the roof of a building or the top of a tall pole, for instance). Unfortunately, the static spike acts like a vertical sail. Wind blows past the static spike and causes a condition called vortex shedding, which is an oscillating flow that takes place when a fluid such as air or water flows past a body at certain velocities. During vortex shedding, vortices are created at the back of the body (in this case the static spike) and detach periodically from either side of the body. The fluid flow past the body creates alternating low-pressure vortices on the downstream side of the body. The body will tend to move toward the low-pressure zone. If the body is not mounted rigidly and the frequency of vortex shedding matches the resonance frequency of the body, the body can begin to resonate, vibrating with harmonic oscillations driven by the energy of the flow. This vibration can ultimately lead to the stress fracture of the weld joint between the body (the static spike) and its supporting flange, resulting in fatigue failure at the weld joint.